Kubernetes is a powerful container orchestration platform that provides several features to help with application deployment and scaling. Two important concepts in Kubernetes are traffic splitting and shadow deployments, which allow you to control traffic distribution and perform test deployments without affecting users. In this blog post, we will explore how to implement traffic splitting and shadow deployments for Java applications on Kubernetes.

Traffic Splitting

Traffic splitting is the ability to distribute traffic between multiple versions of an application running in Kubernetes. This can be useful when rolling out new features or performing A/B testing. To implement traffic splitting for a Java app on Kubernetes, we can use Istio, an open-source service mesh platform.

1. Install Istio: Start by installing Istio in your Kubernetes cluster. You can follow the official Istio documentation for installation instructions.

2. Deploy Multiple Versions: Deploy multiple versions of your Java application as separate Kubernetes deployments. Each version will have its own deployment.yaml file with the necessary configuration, such as container image, environment variables, and replicas.

3. Define a Virtual Service: Define a virtual service in Istio that will be used to split the traffic between the different versions of your application. The virtual service configuration will specify the rules for traffic splitting, such as the percentage of traffic each version should receive.

4. Modify Destination Rules: Modify the destination rules in Istio to define subsets for each version of your application. This allows Istio to route traffic based on these subsets defined in the destination rules.

5. Apply Traffic Splitting: Apply the traffic splitting configuration by applying the virtual service and destination rules to your cluster using kubectl apply -f command.

With traffic splitting configured, the incoming requests to your Java application will be distributed between the different versions based on the rules defined in the virtual service.

Shadow Deployments

Shadow deployments allow you to deploy a new version of your Java application alongside the existing production version without affecting users. The shadow deployment receives the same traffic as the production version but does not serve responses to users. This is useful for testing new releases in a real production environment without any risk.

To implement shadow deployments for a Java app on Kubernetes:

1. Create a Canary Deployment: Create a new deployment for the new version of your Java application. The deployment should have the necessary configuration, such as container image, environment variables, and replicas. However, the replicas should be set to zero initially, so the deployment doesn’t serve any traffic.

2. Modify Service Configuration: Create a service in Kubernetes to expose your Java application. Modify the service configuration to include the selector for both the production deployment and the canary deployment. This allows the service to send traffic to both deployments.

3. Gradually Scale up Canary Deployment: Gradually scale up the replicas of the canary deployment to start receiving a portion of the traffic. Use monitoring and metrics to ensure the new version is performing as expected before scaling up further.

4. Compare and Analyze Results: Analyze the metrics and compare the responses of the canary deployment with the production deployment to identify any issues or discrepancies. Based on the analysis, you can decide to promote the canary deployment as the new production version or roll it back if any problems are detected.

By implementing shadow deployments, you can test new versions of your Java application in a controlled manner and gain confidence before fully rolling out the changes to your users.

Conclusion

Traffic splitting and shadow deployments are powerful techniques that allow you to control traffic distribution and test new releases safely. When using Kubernetes for Java applications, Istio can be utilized to implement traffic splitting, while shadow deployments can be achieved by creating canary deployments and modifying service configurations. By leveraging these techniques, you can confidently deploy and scale your Java apps on Kubernetes while minimizing user impact and ensuring a smooth application delivery process.

#hashtags: #JavaOnKubernetes #TrafficSplittingShadowDeployments